Ash Alert?

In April, Iceland’s Eyjafjallajokull volcano prompted more than 100,000 flight cancellations, costing the airline industry at least $1.7 billion. We couldn’t help but wonder: Could either Kilauea or Mauna Loa produce an ash cloud of this magnitude? We spoke to Mike Poland, geophysicist at the U.S.G.S. Hawaiian Volcano Observatory, to find out.

Why was Iceland’s volcanic eruption so rich in ash?

There were hundreds of feet of ice at the summit of this volcano. As soon as lava started erupting beneath that ice cap, it began to melt, and then water and lava started interacting, and that’s going to explode every time. This mix created great, big ash plumes.

Could a similar eruption happen at Mauna Loa?

Mauna Loa last erupted in 1984, and right now it’s in the longest period of time between eruptions that we know of in the last 200 years. It will certainly erupt again, but even if there was an eruption in winter, when Mauna Loa has a heavy amount of snow, there wouldn’t be the same explosive mix because Mauna Loa would only have a measly amount of snow, at most six feet, versus densely packed ice like at Iceland’s volcano.

What about Kilauea?

Kilauea has erupted explosively in the past and we believe that’s because there were times when Kilauea lavas were mixing with lots of ground water. For example, in 1924 there was a series of explosions because magma drained out of Kilauea’s summit and into the volcano’s plumbing system and then shot out the east rift zone. That “magma draining” caused Halemaumau, which was a cone, to collapse and become a crater. Because the magma drained away from the summit, the water that had been kept out by the heat started to get into the system and in touch with hot rock. When water gets in touch with hot rock, it flashes to steam and you get explosions.

Could an explosion of Iceland’s magnitude ever happen at Kilauea if enough water interacted with lava?

You’d have to have a pretty substantial change in the way Kilauea or even Mauna Loa are behaving in order to get that kind of activity here. Such as, you’d have to have a large collapse at Kilauea that would bring water back into the caldera.